The present invention concerns a tubular apparatus, in particular a steam generator, in the casing of which straight or U-shaped tubes are installed which are maintained at a certain distance from each other by unevenly spaced gratings, with the grating bars being fastened in a frame encircling the tube bundle.
Gratings of this type are to eliminate vibrations and prevent any contact of the tubes of the bundle, which are arranged in parallel with a certain clearance. With previously known tubular apparatuses the grating bars are fixed to the frame by welding. As a consequence the gratings are relatively rigid. Further, steam generators are known in which special support beams consisting of steel flats and crossing each other are welded to the frame. These support beams are provided with slots into which the grating bars, which in this case are also welded to the frame, are inserted.
Gratings of this type are fabricated outside the tubular apparatus. As, for reasons of fabrication, the tube bundle cannot be installed in various instances before the shell of the tubular apparatus has been fixed to the tube sheet, the tubes of the bundle must be inserted through the gratings. With tubular apparatuses having a large shell diameter, help in inserting the bars can be given by members of the assembly staff provided manways permitting access are arranged in the grating structures.